Question

There are 6 books of physics, 3 of chemistry and 4 of biology. Number of ways in which these books can be placed on a shelf if the books of the same subject are to be together is

Answer 1

We need to arrange book such that books of same subjects are together

The units of physics, chemistry and biology books can be arranged in =3! Ways

​​​​​​In set of physics book, the books can be arranged in 6! Ways=720 ways

In set of chemistry book, the books can be arranged in 3! Ways= 6 ways

In set of biology book, they can be arranged in 4! Ways=24 ways

The total number of ways the books can be arranged=3!×6!×3!×4!
=622080 ways